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Simrad AP25 Autopilot
164 20221495F
9 GLOSSARY
Apparent wind – The speed and direction from which the wind
appears to blow with reference to the bow when the boat is
moving (also called relative wind).
Arrival alarm – An alarm signal issued by a GPS/chartplotter
that indicates arrival at or at a predetermined distance from a
waypoint. (see arrival circle).
Arrival circle – An artificial boundary placed around the
destination waypoint of the present navigation leg, the entering
of which will signal an arrival alarm.
Bearing – The horizontal direction of one terrestrial point from
another, expressed as the angular distance from a reference
direction, usually measured from 000° at the reference direction
clockwise through 359°.
BPW – Bearing to a specified waypoint from present position.
BWW – Bearing waypoint to waypoint - Bearing angle of the
line between the “TO” and the “FROM” waypoint, calculated at
the “FROM” waypoint for any two arbitrary waypoints.
COG - Course Over Ground - The actual direction of progress
of a vessel, between two points, with respect to the surface of the
earth, The vessel’s heading may differ from the course over
ground due to the effects of wind, tide, currents.
GPS - Global Positioning System - This system is based on
satellites in fixed orbits, circling the earth at an altitude of
approximately 20,200 km. The system will provide the user with
24 hour a day all weather position coverage, with an accuracy of
5 to 30 meters.
Magnetic bearing – Bearing relative to magnetic north;
compass bearing corrected for deviation.
Magnetic deviation – A local magnetic field onboard a vessel.
Can interfere with the earth’s magnetic field and create compass
readings that may deviate from the actual magnetic heading. The
deviation will vary with the actual heading.
Magnetic heading – heading relative to magnetic north.